CA1207706A - Electrode of particles including boron valve metal, or iron group and active particles - Google Patents
Electrode of particles including boron valve metal, or iron group and active particlesInfo
- Publication number
- CA1207706A CA1207706A CA000396683A CA396683A CA1207706A CA 1207706 A CA1207706 A CA 1207706A CA 000396683 A CA000396683 A CA 000396683A CA 396683 A CA396683 A CA 396683A CA 1207706 A CA1207706 A CA 1207706A
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- Prior art keywords
- particles
- matrix material
- layer
- active particles
- weight
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
- C25B11/04—Electrodes; Manufacture thereof not otherwise provided for characterised by the material
- C25B11/051—Electrodes formed of electrocatalysts on a substrate or carrier
- C25B11/073—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material
- C25B11/091—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material consisting of at least one catalytic element and at least one catalytic compound; consisting of two or more catalytic elements or catalytic compounds
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
- C25B11/02—Electrodes; Manufacture thereof not otherwise provided for characterised by shape or form
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
- C25B11/04—Electrodes; Manufacture thereof not otherwise provided for characterised by the material
- C25B11/051—Electrodes formed of electrocatalysts on a substrate or carrier
- C25B11/055—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the substrate or carrier material
- C25B11/057—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the substrate or carrier material consisting of a single element or compound
- C25B11/061—Metal or alloy
- C25B11/063—Valve metal, e.g. titanium
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B9/00—Cells or assemblies of cells; Constructional parts of cells; Assemblies of constructional parts, e.g. electrode-diaphragm assemblies; Process-related cell features
- C25B9/17—Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof
- C25B9/19—Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof with diaphragms
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/30—Hydrogen technology
- Y02E60/36—Hydrogen production from non-carbon containing sources, e.g. by water electrolysis
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Electrodes For Compound Or Non-Metal Manufacture (AREA)
- Battery Electrode And Active Subsutance (AREA)
- Coating By Spraying Or Casting (AREA)
- Inert Electrodes (AREA)
- Secondary Cells (AREA)
- Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
- Superconductors And Manufacturing Methods Therefor (AREA)
- Surgical Instruments (AREA)
- Electric Double-Layer Capacitors Or The Like (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
An electrode of the type of a composite product has a layer of matrix particles, applied to a base by a thermal spraying process. Electrochemically active particles having a particle size smaller by at least one order of magnitude are surface bonded to the matrix particles prior to the spraying onto the base. The disclosed electrocatalyst is metal of the platinum or iron groups. The matrix particles are conductive but have a lesser electrochemical activity than that of the active particles. The matrix material is selected from the group consisting of oxides and carbides of titanium.
An electrode of the type of a composite product has a layer of matrix particles, applied to a base by a thermal spraying process. Electrochemically active particles having a particle size smaller by at least one order of magnitude are surface bonded to the matrix particles prior to the spraying onto the base. The disclosed electrocatalyst is metal of the platinum or iron groups. The matrix particles are conductive but have a lesser electrochemical activity than that of the active particles. The matrix material is selected from the group consisting of oxides and carbides of titanium.
Description
STATE OF THE ART
German Paten~ No. 1,671,422, published February 17, 1983 and issued to Diamond Shamrock Technologies S.A., and No. ~,300,422, published October 15, 1981 and issued to Hoechst ~G, relate to dimensionally stable electrodes prepared by thermal spraying with subsequent application of the electrocatalytic agent, but thermal spraying by flame spraying and plasma jet application produces a layer of rnore or less porosity. If the porosity of the layer is too low, the desired electrochemical reaction with the electrode can only take place on the surface of the electrode layer. If the porosity of the layer is greater, the electrocatalytic agent subsequently applied to the layer will penetrate the layer more deeply in the direction of the electrode base but with decreasing concentration.
If the outer layer is too porous, the electrode base is exposed to the cell conditions and the base is not adequately protected under operating conditions in the cell from the effect of the electrolysis products. Even if the thermally sprayed layer had an ideal density and porosity, the electro-catalytic agent subsequently applied is predominantly only on the external surface of the layer and becomes rapidly eroded whereby the electrode becomes passivated. Moreover, the prior art has the disadvantage of requiring the thermal spraying and activation to be carried out in two separate steps.
OBJECTS OF THE INVENTION
It is an object of the invention to provide novel electrodes having prolonged operation characteristics and a ~P~3~
method of preparing the said electrodes~
It is another object o~ t~e invention to provide a novel electrolysis ce.ll containing at least one electrode of the invention as its anode and~or cathode.
It is a further object o~ the invention to provide a novel method of electrolysis of an aqueous electrolyte.
Th.ese and other objects and advantages of the invention will become obvious from the following detailed description.
- ~HE INVENTI~N
_ In one aspect the invention provides novel co~posite electrodes comprised o~ an electroconductive base with an electrolyte inert, electroconductive, electrocatalytic layer applied to the base by thermal spraying, the said layer being a powder o~ matrix material particles selected from th.e group consisting of oxides, nitrides, phosph.ides, silicides, borides and carbides of a metal selected from the group consisting of boron, valve metals and iron group metals, said matrix material particles having substantially uniformly deposited thereon electrocatalytically active particles of a metal selected from the group consisting of platinum group metals and iron group metals and o*ides thereof, said active particles having a particle size smaller by at least one order of magnitude than the particle size of the matri~ material particles.
In a pre~erred elec~rode according to the invention the electrsconductive ~ase is sele.cted ~rom graphite, metals and alloys th.ereof, iron group me'als and their alloys being preferred; ~e matrix material is selected from oxides and car~ides of titanium, sub-stoichiometric ti~anium oxide (:TiO2 xJ ~ing particularly advantageous; and the electrocatalytical.ly active par~icles are selected from the platinum group metals.
. In a second aspect the invention provides an electrolytic cell comprising a housing with an anode and a cathode forming an interelectrodic gap and optionally h.aving a membrane or diaphxagm therein~ at least one composite electrode comprising an electroconductive base with an electrolyte inert, electroconductive electro-catalytic layer applied to the base by thermal spraying, said layer being formed of matrix material particles in powder form, and matrix material being selected from the :group consisting of oxides and carbides of titanium, said matrix material particles having substantially uniformly deposited th.ereon electrocatalytically active particles of a metal selected from the group consisting of platinum group metals and iron group metals and oxides thereof, said active particles having a particle si.ze smaller by at least one order of magnitude than the particle size of the matrix particles.
-3a-Q~ n~
In a further aspect the invention provides a process of electrolyzing an aqueous electrolyte containing chloride ions or sul~ate ions by impressing an electrolysis current on an anode and a cathode with the electrolyte between them, wherein at least one of the anode or cathode is a composite electrode according to the invention.
The homogeneous distri~ution of the smaller electro~
catalytic particles over the much larger matrix particles results in the two layer components being superficially bonded togethex and the resulting powder for thermal spraying has the advantages of allowing the active layer to be applied in a single operation. Moreover, the resulting layer has the electrocatalytic agent distributed uniformly throughout the layer offering a very large active surface area and mechanical abrasion of the layer does not lead to rapid passivation as the new surface contains additional electrocatalytic agent resulting in a new active surface.
The layer i5 preferably 50 to 110 microns, more pre-ferably 80 to 110 microns thick. If the layer is too thin, the electrode base may not be adequately coated resulting in an electrode with a short operating life and the layer will ~ot have sufficient mechanical strength, especially resistance to abrasion. If the coating layer of the electrode is too thick, the electrode becomes too expensive.
-3b-~z~
The ~etals used to ~ox~ the Po~dered m~triX ~ay be boron, iron gxoup met~ls such as iro~, cobAlt and ~ickel and valve metals such as titanium, ta~talum, vanadium~
zirconium and niobium and alloys thereof in the form of their oxides, nitrides, phosphides, borides, silicides and carbides~
A preferred ahode matrix for the electrolysis of alkali metal halide electrolyte, especially sodium chloride to produce chlorine, is titanium oxide since it is a commercially available product with broad uses such as sintering although tantalum oxide is also useful.
A preferred matrix when theelectrode is to he used as a cathode in the electrolysis of alkali metal chloride electrolytes comprises particles of the metals of the iron group such as nickel oxide, nick~l carbide, cobalt oxide or cobalt carbide. ~he electrocatalytic agent with a particle size smaller by at least one order of magnitude is uniformly applied to the matrix. The .~
l i 7 ~ ~
resulting powder is then preferably applied to a cathode base material suoh as ~teel or similar materials by ther~al spray-,ing. Also useful ~or cathodes is magnetite or other iron ioxides coated with a pla~inum group metal.
Il The electocatalytic agent may be a platinum group metal such as platinum, palladium, ruthenium, rhodium, osmium ~¦or iridium or an iron gr~ metal such as iron, cobalt or nicke 1 !, and oxides thereof, The said agent is in the form of particle ¦at least one order of magnitude less ~han ~he matrix particle~.
and preferably 20 to ~0 times smallex.
The amount of said agent for economical reasons shouId be kept as 1~ as possible but should be sufficiently high so as not to 'impair the desired properties of the electrode. Preferably, ~the coatiny contains 1 to 5%, most preferably 1 to 3%, by ;~'weight of the powder layer on the electrode.
The thermally applied layer may also contain a third', ! agent to pro~ide desirable properties to the layer such as ,i imechanical streng$h to provide resistan~eto abrasion at the lilayer surface. For these purposes, the layer may contain 5 to !!50% by weight of the layer of mechanically resi~tant materials such as ceramic, vitreous or glass like materials such as glals ,ceramic components.
To reduce the amount of costly ~latinum group metals 'to a minimum, the electrocatal~tic agent on the matrix is ~ "distributed in such a ternary layer so that the amount of electrocatalytic particles increases from ~he interior to the exterior of the layer. An example of a suitable gradient is illustrated in the followiny Table with the layer surface on ', the electro~onductive hase containing no electrocatalyti~
agent and the outer surface containing no ternary agent of titanium dioxide.
;5-~7~
. 1 . I
TABLE I
!' . ~
. _ % T~ t ~ % q~io2 ~ Interior ~
." Surface on base0 100 1, 20 ~0 ~0 I' Exterior ~urface 100 D
Il 1- .__ ~
' A concentration gradient of the ~y~e in Table I can ,Ibe easily predetermined with the use of known proportionating ¦'equipment for the independent feeding o~ ~wo com~onents to a ¦
¦ithermal spraying apparatus. If desired, the concentration . __ ¦~gradient may be uniform or varied to other ra~io~. !
l~ In a preferred process of the invention for the Pre-, I,~paration of the powder used to form the electroae layer, a 1, ! soluble salt of the ~lectrocatalytic agent is dis501ved i~-a !
~low-boiling point solvent and the powdered matrix is placed llin the solution and the mixture is stirred at 50 to 10C
1, below the boiling point of the solvent after which the ~olvent is evaporated. When the p~wder is almost dry7 it!is dried in !
an oven at a temperature 10 to 40~C higher ~han the solvent boiling point for one to 4 hours. The powder is then ground to crush any agglomerates that may have ormedwhile beLng ~arefuI
not to change the original grain size and the powder is then , heated at temperatures suff.iciently high to thermally deco se the salt and form the electrocatalytic agent. The ~hermal .
!
I' . I
!i ¦
~;decomposition may be effected in an oxidizing atmosphere or an ,inert atmosphere.
, For commerical scale, ~he deposition of the electro-~catalytic agent on the matrix particles may be effected in a Ifluidized bed with ~he salt solution being ~prayed on a fluidiæed bed of the matrix particles with ~ counter-flow ! mist. The particles to form the layer have the makrix ¦p~rticle~ coated as uniformly as possible with ~he electro-¦lcatalytic agent but not necessarily with a dense coating. The 10. ,~particles of the electrocatalytic a~ent are to be regularly l,distributed on the surace of the matrix particles~
¦. The electroconductive base may be made of any suitab e ¦,material in a~y desired form. The ~ase may be made of graphite,s !~ valve metals such as titanium or tantalum or steel or other ¦~ iron alloys depending on whether the electrode is to be used !
! as an anode ox a cathode7 The base may be in the f orm of a ! ¦' sheet~mesh, rods, etc.~ ~
¦~ The electrolytic cell of the invention is comprised ¦
~' of a h~usi~g containing an anode and a cathode forming an.inter-1 electrodic gap optionally with a membrane or diaphragm therein j at least one of the said anode or cathode being an electrode of the invention as discussed above.
~I The novel electrolysis process of the invention com-prises passin~ an electrolysis current betwean an anode and a cathode with an aqueous electroly~e there~etwee~, a~ leas~ one of said anode and cathode being an electrode o~ the invention as discussed above. The aqueous e~ec~rolyte preferably is an alkali metal chloride solution or sulfuric acid electrolyte.
: !
~Z~!~7~
Re:Eerring now t ~h- r ng.
j~ The ~ig~ is a partial schema~ic illustration of an electrode of the invention with an electrically conductive llbase 1 on which a layer of composi~e powdex has been ~hermall~
Il,spra~ed. The ~arger matrix particles 2 have supericially and homogeneously deposited thereon elec~rocatalytic particles 1~3 whi~h are smaller by an order of magnitude~ pre~erably 20 ( Ito S0 times smaller.
~ In the following example ~h re are described several preferred em~odiments to illustrate the invention ~owever~
¦lik shouId ~e understood that the invention is not intended to~
¦jbe limited to the specific embodiments.
I'' . I
EXAMPLE i li 100 g of non-stoichiometric titanium oxide powd~r ¦iwith a grain size of -100 +37 mesh wer~ ~laced in an ! 11 evaporating dish and a solution of 2.5 q of hexachloroplatinate in 120 ml of methanol was added thereto. The methanol was l~evaporated ~hile s~irring the mixture over a water bath and ¦Iwhen the mixture was almost completely dry, the evaporating ,,dish was placed in a dr~ing oven at 105C for 2 hours. The resulting powdex was then lightly crushed with a mortar to .reduce any agglomerates to the original grain size and the powder was then heated at 550C for 4 hours in a crucible in !
a muffle. The cooled ~owder was again l.ightly ground to its original size and the powder was screened for a grain size of . -100 +37 mesh.
'' ' .. I
¦ A titanium sheet measuring 30mm x 120 mm ~r 2 mm was ¦
'sandblasted with normal corundum containing 3~ titanium oxide 'and the sheet was coated with the above obtained powder using~
la plasma burnerncdel F-4 of Plasmatechnik~Company. The plasma ¦~operating conditions were a current of 400A~ avoltage of 70V
¦,and a plasma gas consisting of 26 liters of nitrogen per minute and 2 liters of hydrogen per minute. The spraying distance-was 150 mm and the resultin~ layer on the titanium llsheet was 100 mm.
j' Electrodes as produeed above were used as the cathod ¦and anode in a laboratory cell with an electrode gap of 6.5 cmj and a current density of 100 A/m2 for electrolysis of 10%
¦Isulfuric acid at 20C~ After one month of operation~ the ¦cell potential of 2.56 volts was unchanged.
~1 Various modifi~ations of the electrodes and cells lland electrolysis process of the invention may be made without ( ¦'de~arting from the spirit or scope thereof and it is to be understood that the invention is intended to be limited only as defined in the appended claims.
_g_
German Paten~ No. 1,671,422, published February 17, 1983 and issued to Diamond Shamrock Technologies S.A., and No. ~,300,422, published October 15, 1981 and issued to Hoechst ~G, relate to dimensionally stable electrodes prepared by thermal spraying with subsequent application of the electrocatalytic agent, but thermal spraying by flame spraying and plasma jet application produces a layer of rnore or less porosity. If the porosity of the layer is too low, the desired electrochemical reaction with the electrode can only take place on the surface of the electrode layer. If the porosity of the layer is greater, the electrocatalytic agent subsequently applied to the layer will penetrate the layer more deeply in the direction of the electrode base but with decreasing concentration.
If the outer layer is too porous, the electrode base is exposed to the cell conditions and the base is not adequately protected under operating conditions in the cell from the effect of the electrolysis products. Even if the thermally sprayed layer had an ideal density and porosity, the electro-catalytic agent subsequently applied is predominantly only on the external surface of the layer and becomes rapidly eroded whereby the electrode becomes passivated. Moreover, the prior art has the disadvantage of requiring the thermal spraying and activation to be carried out in two separate steps.
OBJECTS OF THE INVENTION
It is an object of the invention to provide novel electrodes having prolonged operation characteristics and a ~P~3~
method of preparing the said electrodes~
It is another object o~ t~e invention to provide a novel electrolysis ce.ll containing at least one electrode of the invention as its anode and~or cathode.
It is a further object o~ the invention to provide a novel method of electrolysis of an aqueous electrolyte.
Th.ese and other objects and advantages of the invention will become obvious from the following detailed description.
- ~HE INVENTI~N
_ In one aspect the invention provides novel co~posite electrodes comprised o~ an electroconductive base with an electrolyte inert, electroconductive, electrocatalytic layer applied to the base by thermal spraying, the said layer being a powder o~ matrix material particles selected from th.e group consisting of oxides, nitrides, phosph.ides, silicides, borides and carbides of a metal selected from the group consisting of boron, valve metals and iron group metals, said matrix material particles having substantially uniformly deposited thereon electrocatalytically active particles of a metal selected from the group consisting of platinum group metals and iron group metals and o*ides thereof, said active particles having a particle size smaller by at least one order of magnitude than the particle size of the matri~ material particles.
In a pre~erred elec~rode according to the invention the electrsconductive ~ase is sele.cted ~rom graphite, metals and alloys th.ereof, iron group me'als and their alloys being preferred; ~e matrix material is selected from oxides and car~ides of titanium, sub-stoichiometric ti~anium oxide (:TiO2 xJ ~ing particularly advantageous; and the electrocatalytical.ly active par~icles are selected from the platinum group metals.
. In a second aspect the invention provides an electrolytic cell comprising a housing with an anode and a cathode forming an interelectrodic gap and optionally h.aving a membrane or diaphxagm therein~ at least one composite electrode comprising an electroconductive base with an electrolyte inert, electroconductive electro-catalytic layer applied to the base by thermal spraying, said layer being formed of matrix material particles in powder form, and matrix material being selected from the :group consisting of oxides and carbides of titanium, said matrix material particles having substantially uniformly deposited th.ereon electrocatalytically active particles of a metal selected from the group consisting of platinum group metals and iron group metals and oxides thereof, said active particles having a particle si.ze smaller by at least one order of magnitude than the particle size of the matrix particles.
-3a-Q~ n~
In a further aspect the invention provides a process of electrolyzing an aqueous electrolyte containing chloride ions or sul~ate ions by impressing an electrolysis current on an anode and a cathode with the electrolyte between them, wherein at least one of the anode or cathode is a composite electrode according to the invention.
The homogeneous distri~ution of the smaller electro~
catalytic particles over the much larger matrix particles results in the two layer components being superficially bonded togethex and the resulting powder for thermal spraying has the advantages of allowing the active layer to be applied in a single operation. Moreover, the resulting layer has the electrocatalytic agent distributed uniformly throughout the layer offering a very large active surface area and mechanical abrasion of the layer does not lead to rapid passivation as the new surface contains additional electrocatalytic agent resulting in a new active surface.
The layer i5 preferably 50 to 110 microns, more pre-ferably 80 to 110 microns thick. If the layer is too thin, the electrode base may not be adequately coated resulting in an electrode with a short operating life and the layer will ~ot have sufficient mechanical strength, especially resistance to abrasion. If the coating layer of the electrode is too thick, the electrode becomes too expensive.
-3b-~z~
The ~etals used to ~ox~ the Po~dered m~triX ~ay be boron, iron gxoup met~ls such as iro~, cobAlt and ~ickel and valve metals such as titanium, ta~talum, vanadium~
zirconium and niobium and alloys thereof in the form of their oxides, nitrides, phosphides, borides, silicides and carbides~
A preferred ahode matrix for the electrolysis of alkali metal halide electrolyte, especially sodium chloride to produce chlorine, is titanium oxide since it is a commercially available product with broad uses such as sintering although tantalum oxide is also useful.
A preferred matrix when theelectrode is to he used as a cathode in the electrolysis of alkali metal chloride electrolytes comprises particles of the metals of the iron group such as nickel oxide, nick~l carbide, cobalt oxide or cobalt carbide. ~he electrocatalytic agent with a particle size smaller by at least one order of magnitude is uniformly applied to the matrix. The .~
l i 7 ~ ~
resulting powder is then preferably applied to a cathode base material suoh as ~teel or similar materials by ther~al spray-,ing. Also useful ~or cathodes is magnetite or other iron ioxides coated with a pla~inum group metal.
Il The electocatalytic agent may be a platinum group metal such as platinum, palladium, ruthenium, rhodium, osmium ~¦or iridium or an iron gr~ metal such as iron, cobalt or nicke 1 !, and oxides thereof, The said agent is in the form of particle ¦at least one order of magnitude less ~han ~he matrix particle~.
and preferably 20 to ~0 times smallex.
The amount of said agent for economical reasons shouId be kept as 1~ as possible but should be sufficiently high so as not to 'impair the desired properties of the electrode. Preferably, ~the coatiny contains 1 to 5%, most preferably 1 to 3%, by ;~'weight of the powder layer on the electrode.
The thermally applied layer may also contain a third', ! agent to pro~ide desirable properties to the layer such as ,i imechanical streng$h to provide resistan~eto abrasion at the lilayer surface. For these purposes, the layer may contain 5 to !!50% by weight of the layer of mechanically resi~tant materials such as ceramic, vitreous or glass like materials such as glals ,ceramic components.
To reduce the amount of costly ~latinum group metals 'to a minimum, the electrocatal~tic agent on the matrix is ~ "distributed in such a ternary layer so that the amount of electrocatalytic particles increases from ~he interior to the exterior of the layer. An example of a suitable gradient is illustrated in the followiny Table with the layer surface on ', the electro~onductive hase containing no electrocatalyti~
agent and the outer surface containing no ternary agent of titanium dioxide.
;5-~7~
. 1 . I
TABLE I
!' . ~
. _ % T~ t ~ % q~io2 ~ Interior ~
." Surface on base0 100 1, 20 ~0 ~0 I' Exterior ~urface 100 D
Il 1- .__ ~
' A concentration gradient of the ~y~e in Table I can ,Ibe easily predetermined with the use of known proportionating ¦'equipment for the independent feeding o~ ~wo com~onents to a ¦
¦ithermal spraying apparatus. If desired, the concentration . __ ¦~gradient may be uniform or varied to other ra~io~. !
l~ In a preferred process of the invention for the Pre-, I,~paration of the powder used to form the electroae layer, a 1, ! soluble salt of the ~lectrocatalytic agent is dis501ved i~-a !
~low-boiling point solvent and the powdered matrix is placed llin the solution and the mixture is stirred at 50 to 10C
1, below the boiling point of the solvent after which the ~olvent is evaporated. When the p~wder is almost dry7 it!is dried in !
an oven at a temperature 10 to 40~C higher ~han the solvent boiling point for one to 4 hours. The powder is then ground to crush any agglomerates that may have ormedwhile beLng ~arefuI
not to change the original grain size and the powder is then , heated at temperatures suff.iciently high to thermally deco se the salt and form the electrocatalytic agent. The ~hermal .
!
I' . I
!i ¦
~;decomposition may be effected in an oxidizing atmosphere or an ,inert atmosphere.
, For commerical scale, ~he deposition of the electro-~catalytic agent on the matrix particles may be effected in a Ifluidized bed with ~he salt solution being ~prayed on a fluidiæed bed of the matrix particles with ~ counter-flow ! mist. The particles to form the layer have the makrix ¦p~rticle~ coated as uniformly as possible with ~he electro-¦lcatalytic agent but not necessarily with a dense coating. The 10. ,~particles of the electrocatalytic a~ent are to be regularly l,distributed on the surace of the matrix particles~
¦. The electroconductive base may be made of any suitab e ¦,material in a~y desired form. The ~ase may be made of graphite,s !~ valve metals such as titanium or tantalum or steel or other ¦~ iron alloys depending on whether the electrode is to be used !
! as an anode ox a cathode7 The base may be in the f orm of a ! ¦' sheet~mesh, rods, etc.~ ~
¦~ The electrolytic cell of the invention is comprised ¦
~' of a h~usi~g containing an anode and a cathode forming an.inter-1 electrodic gap optionally with a membrane or diaphragm therein j at least one of the said anode or cathode being an electrode of the invention as discussed above.
~I The novel electrolysis process of the invention com-prises passin~ an electrolysis current betwean an anode and a cathode with an aqueous electroly~e there~etwee~, a~ leas~ one of said anode and cathode being an electrode o~ the invention as discussed above. The aqueous e~ec~rolyte preferably is an alkali metal chloride solution or sulfuric acid electrolyte.
: !
~Z~!~7~
Re:Eerring now t ~h- r ng.
j~ The ~ig~ is a partial schema~ic illustration of an electrode of the invention with an electrically conductive llbase 1 on which a layer of composi~e powdex has been ~hermall~
Il,spra~ed. The ~arger matrix particles 2 have supericially and homogeneously deposited thereon elec~rocatalytic particles 1~3 whi~h are smaller by an order of magnitude~ pre~erably 20 ( Ito S0 times smaller.
~ In the following example ~h re are described several preferred em~odiments to illustrate the invention ~owever~
¦lik shouId ~e understood that the invention is not intended to~
¦jbe limited to the specific embodiments.
I'' . I
EXAMPLE i li 100 g of non-stoichiometric titanium oxide powd~r ¦iwith a grain size of -100 +37 mesh wer~ ~laced in an ! 11 evaporating dish and a solution of 2.5 q of hexachloroplatinate in 120 ml of methanol was added thereto. The methanol was l~evaporated ~hile s~irring the mixture over a water bath and ¦Iwhen the mixture was almost completely dry, the evaporating ,,dish was placed in a dr~ing oven at 105C for 2 hours. The resulting powdex was then lightly crushed with a mortar to .reduce any agglomerates to the original grain size and the powder was then heated at 550C for 4 hours in a crucible in !
a muffle. The cooled ~owder was again l.ightly ground to its original size and the powder was screened for a grain size of . -100 +37 mesh.
'' ' .. I
¦ A titanium sheet measuring 30mm x 120 mm ~r 2 mm was ¦
'sandblasted with normal corundum containing 3~ titanium oxide 'and the sheet was coated with the above obtained powder using~
la plasma burnerncdel F-4 of Plasmatechnik~Company. The plasma ¦~operating conditions were a current of 400A~ avoltage of 70V
¦,and a plasma gas consisting of 26 liters of nitrogen per minute and 2 liters of hydrogen per minute. The spraying distance-was 150 mm and the resultin~ layer on the titanium llsheet was 100 mm.
j' Electrodes as produeed above were used as the cathod ¦and anode in a laboratory cell with an electrode gap of 6.5 cmj and a current density of 100 A/m2 for electrolysis of 10%
¦Isulfuric acid at 20C~ After one month of operation~ the ¦cell potential of 2.56 volts was unchanged.
~1 Various modifi~ations of the electrodes and cells lland electrolysis process of the invention may be made without ( ¦'de~arting from the spirit or scope thereof and it is to be understood that the invention is intended to be limited only as defined in the appended claims.
_g_
Claims (25)
1. A composite electrode comprising an electroconductive base with an electrolyte inert, electroconductive electrocatalytic layer applied to the base by thermal spraying, said layer having a thickness of 50 microns or more and being formed of matrix material particles in powder form, said matrix material being selected from the group consisting of oxides and carbides of titanium, said matrix material particles having sub-stantially uniformly deposited thereon electrocatalytically active particles of a metal selected from the group consist-ing of platinum group metals and iron group metals and oxides thereof, said active particles having a particle size smaller by at least one order of magnitude than the particle size of the matrix material particles.
2. An electrode of claim 1, wherein the electroconductive base is selected from the group consisting of graphite, metals and alloys thereof.
3. An electrode of claim 1, wherein the electrocatalytically active particles are deposited on the matrix material particles in an amount of between about 1 and 5% by weight based on the weight of the matrix material.
4. An electrode of claim 3, wherein the matrix material particles consist of a substoichiometric titanium oxide(TiO2-x) and the electrocatalytically active particles consist of a platinum group metal.
5. An electrode of claim 4, wherein the platinum group metal is deposited on the substoichiometric titanium oxide in an amount of between 1 and 3% by weight, based on the weight of the titanium oxide.
6. An electrode of claim 1, wherein the matrix particles are 20 to 50 times larger than the electrocatalytically active particles.
7. An electrode of claim 1, wherein the layer further includes 5 to 50% by weight of mechanically resistant particles.
8. An electrode of claim 7, wherein the electrocatalytically active particles deposited on the matrix material particles are distributed in the layer so that the amount of electrocatalytically active particles increases in the direction from the interior of the layer to the exterior of the layer.
9. In an electrolytic cell comprising a housing with an anode and a cathode forming an inter-electrodic gap at least one composite electrode comprising an electroconductive base with an electrolyte inert, electro-conductive electrocatalytic layer applied to the base by thermal spraying, said layer having thickness of 50 microns or more, said layer being formed of matrix material particles in powder form, and matrix material being selected from the group consisting of oxides and carbides of titanium, said matrix material particles having sub-stantially uniformly deposited thereon electrocatalytically active particles of a metal selected from the group consisting of platinum group metals and iron group metals and oxides thereof, said active particles having a particle size smaller by at least one order of magnitude than the particle size of the matrix material particles.
10. A cell of claim 9, wherein the electro-conductive base is selected from the group consisting of graphite, metals and alloys thereof.
11. A cell of claim 9, wherein the electrocatalytically active particles are deposited on the matrix material particles in an amount of between about 1 and 5% by weight based on the weight of the matrix material.
12. A cell of claim 11, wherein the matrix material particles consist of a substoichiometric titanium oxide (TiO2-x) and the electrocatalytically active particles consist of a platinum group metal.
13. A cell of claim 12, wherein the platinum group metal is deposited on the substoichiometric titanium oxide in an amount of between 1 and 3% by weight, based on the weight of the titanium oxide.
14. A cell of claim 9, wherein the matrix particles are 20 to 50 times larger than the electro-catalytical particles.
15. A cell of claim 9, wherein the layer further includes 5 to 50% by weight of mechanically resistant particles.
16. A cell of claim 15, wherein the electro-catalytically active particles deposited on the matrix material particles are distributed in the layer so that the amount of electrocatalytically active particles increases in the direction from the interior of the layer to the exterior of the layer.
17. A cell of claim 9, having a membrane in the electrodic gap.
18. In the process of electrolyzing an aqueous electrolyte containing chloride ions or sulfate ions by impressing an electrolysis current on an anode and a cathode with the electrolyte between them the improvement comprising at least one of the anode or cathode being a composite electrode comprising an electroconductive base with an electrolyte inert, electroconductive electrocatalytic layer applied to the base by thermal spraying, said layer having thickness of 50 microns or more; said layer being formed of matrix material particles in powder form, said matrix material being selected from the group consisting of oxides and carbides of titanium, said matrix material particles having substantially uniformly deposited thereon electrocatalytically active particles of a metal selected from the group consisting of platinum group metals and iron group metals and oxides thereof, said active particles having a particle size smaller by at least one order of magnitude than the particle size of the matrix material particles.
19. A process of claim 18, wherein the electroconductive base is selected from the group consisting of graphite, metals and alloys thereof.
20. A process of claim 18, wherein the electrocatalytically active particles are deposited on the matrix material particles in an amount of between about 1 and 5% by weight based on the weight of the matrix material.
21. A process of claim 20, wherein the matrix material particles consist of a substoichiometric titanium oxide (TiO2-X) and the electrocatalytically active particles consist of a platinum group metal.
22. A process of claim 21 wherein the platinum group metal is deposited on the substoichiometric titanium oxide in an amount of between 1 and 3% by weight, based on the weight of the titanium oxide.
23. A process of claim 18, wherein the matrix particles are 20 to 50 times larger than the electro-catalytically active particles.
24. A process of claim 18, wherein the layer further includes 5 to 50% by weight of mechanically resistant particles.
25. A process of claim 24, wherein the electrocatalytically active particles deposited on the matrix material particles are distributed in the layer so that the amount of electrocatalytically active particles increases in the direction from the interior of the layer to the exterior of the layer.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19813106587 DE3106587A1 (en) | 1981-02-21 | 1981-02-21 | "ELECTRODE" |
| DEP3106587.2-41 | 1981-02-21 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1207706A true CA1207706A (en) | 1986-07-15 |
Family
ID=6125487
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000396683A Expired CA1207706A (en) | 1981-02-21 | 1982-02-19 | Electrode of particles including boron valve metal, or iron group and active particles |
Country Status (9)
| Country | Link |
|---|---|
| US (1) | US4392927A (en) |
| EP (1) | EP0058832B1 (en) |
| JP (1) | JPS57177983A (en) |
| KR (1) | KR890001217B1 (en) |
| AT (1) | ATE19268T1 (en) |
| BR (1) | BR8200929A (en) |
| CA (1) | CA1207706A (en) |
| DE (2) | DE3106587A1 (en) |
| NO (1) | NO158548C (en) |
Families Citing this family (34)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4508788A (en) * | 1982-09-09 | 1985-04-02 | Gte Products Corporation | Plasma spray powder |
| US4584172A (en) * | 1982-09-27 | 1986-04-22 | Aluminum Company Of America | Method of making composition suitable for use as inert electrode having good electrical conductivity and mechanical properties |
| US4454015A (en) * | 1982-09-27 | 1984-06-12 | Aluminum Company Of America | Composition suitable for use as inert electrode having good electrical conductivity and mechanical properties |
| US4544461A (en) * | 1983-03-28 | 1985-10-01 | Energy Conversion Devices, Inc. | Hydrogen sulfide decomposition cell and catalytic materials therefor |
| DE3472979D1 (en) * | 1983-06-28 | 1988-09-01 | Bbc Brown Boveri & Cie | Process for manufacturing a depassivating layer and depassivating layer on an electrode for an electrochemical cell |
| JPS60210514A (en) * | 1984-03-23 | 1985-10-23 | エレクトリツク パワー リサーチ インスチテユート インコーポレーテツド | Electric catalyst containing platinum highly diffused in superfine titanium carbide |
| DE3423605A1 (en) * | 1984-06-27 | 1986-01-09 | W.C. Heraeus Gmbh, 6450 Hanau | COMPOSITE ELECTRODE, METHOD FOR THEIR PRODUCTION AND THEIR USE |
| IT1208128B (en) * | 1984-11-07 | 1989-06-06 | Alberto Pellegri | ELECTRODE FOR USE IN ELECTROCHEMICAL CELLS, PROCEDURE FOR ITS PREPARATION AND USE IN THE ELECTROLYSIS OF DISODIUM CHLORIDE. |
| FR2579628A1 (en) * | 1985-03-29 | 1986-10-03 | Atochem | CATHODE FOR ELECTROLYSIS AND METHOD FOR MANUFACTURING THE SAME CATHODE |
| DE3613997A1 (en) * | 1986-04-25 | 1987-10-29 | Sigri Gmbh | ANODE FOR ELECTROLYTIC PROCESSES |
| JP2825206B2 (en) * | 1988-02-08 | 1998-11-18 | アイースタット コーポレーション | Metal oxide electrode |
| US5314601A (en) * | 1989-06-30 | 1994-05-24 | Eltech Systems Corporation | Electrodes of improved service life |
| US5324407A (en) * | 1989-06-30 | 1994-06-28 | Eltech Systems Corporation | Substrate of improved plasma sprayed surface morphology and its use as an electrode in an electrolytic cell |
| JPH0414784A (en) * | 1990-05-08 | 1992-01-20 | Masao Iwanaga | Electro-discharge element, manufacture and applied device thereof |
| TW197475B (en) * | 1990-12-26 | 1993-01-01 | Eltech Systems Corp | |
| US5716422A (en) * | 1996-03-25 | 1998-02-10 | Wilson Greatbatch Ltd. | Thermal spray deposited electrode component and method of manufacture |
| EP0935265A3 (en) * | 1998-02-09 | 2002-06-12 | Wilson Greatbatch Ltd. | Thermal spray coated substrate for use in an electrical energy storage device and method |
| US6168694B1 (en) * | 1999-02-04 | 2001-01-02 | Chemat Technology, Inc. | Methods for and products of processing nanostructure nitride, carbonitride and oxycarbonitride electrode power materials by utilizing sol gel technology for supercapacitor applications |
| US20030116431A1 (en) * | 2001-12-19 | 2003-06-26 | Akzo Nobel N.V. | Electrode |
| WO2003052168A2 (en) * | 2001-12-19 | 2003-06-26 | Akzo Nobel N.V. | Electrode |
| US7571011B2 (en) * | 2003-05-01 | 2009-08-04 | Second Sight Medical Products, Inc. | Adherent metal oxide coating forming a high surface area electrode |
| US7074253B2 (en) * | 2003-05-20 | 2006-07-11 | Exxonmobil Research And Engineering Company | Advanced erosion resistant carbide cermets with superior high temperature corrosion resistance |
| US7153338B2 (en) * | 2003-05-20 | 2006-12-26 | Exxonmobil Research And Engineering Company | Advanced erosion resistant oxide cermets |
| US7544228B2 (en) * | 2003-05-20 | 2009-06-09 | Exxonmobil Research And Engineering Company | Large particle size and bimodal advanced erosion resistant oxide cermets |
| US7332065B2 (en) * | 2003-06-19 | 2008-02-19 | Akzo Nobel N.V. | Electrode |
| EP1489200A1 (en) * | 2003-06-19 | 2004-12-22 | Akzo Nobel N.V. | Electrode |
| US7871955B2 (en) * | 2004-04-09 | 2011-01-18 | Basf Fuel Cell Gmbh | Platinum catalysts from in situ formed platinum dioxide |
| DE102004047357A1 (en) * | 2004-09-29 | 2006-04-06 | eupec Europäische Gesellschaft für Leistungshalbleiter mbH | Electrical arrangement and method for producing an electrical arrangement |
| FI118159B (en) * | 2005-10-21 | 2007-07-31 | Outotec Oyj | Method for forming an electrocatalytic surface of an electrode and electrode |
| US7798685B2 (en) * | 2007-01-30 | 2010-09-21 | Edmond Matthew P | Motorcycle shock light |
| KR100863725B1 (en) * | 2007-04-25 | 2008-10-16 | 삼성전기주식회사 | Hydrogen generating apparatus and fuel cell power generation system |
| JP6497590B2 (en) * | 2015-02-03 | 2019-04-10 | パナソニックＩｐマネジメント株式会社 | Method of decomposing water, water splitting device and anode electrode for oxygen generation |
| USD826300S1 (en) * | 2016-09-30 | 2018-08-21 | Oerlikon Metco Ag, Wohlen | Rotably mounted thermal plasma burner for thermalspraying |
| DE102018132399A1 (en) * | 2018-12-17 | 2020-06-18 | Forschungszentrum Jülich GmbH | Gas diffusion body |
Family Cites Families (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1195871A (en) * | 1967-02-10 | 1970-06-24 | Chemnor Ag | Improvements in or relating to the Manufacture of Electrodes. |
| DE2100652A1 (en) * | 1971-01-08 | 1972-07-20 | Metallgesellschaft Ag | Electrode for chlor-alkali electrolysis and process for its manufacture |
| DE2300422C3 (en) * | 1973-01-05 | 1981-10-15 | Hoechst Ag, 6000 Frankfurt | Method of making an electrode |
| US4138510A (en) * | 1973-09-27 | 1979-02-06 | Firma C. Conradty | Metal anode for electrochemical processing and method of making same |
| NO141419C (en) * | 1974-02-02 | 1980-03-05 | Sigri Elektrographit Gmbh | ELECTRODE FOR ELECTROCHEMICAL PROCESSES |
| US4049841A (en) * | 1975-09-08 | 1977-09-20 | Basf Wyandotte Corporation | Sprayed cathodes |
| US3992278A (en) * | 1975-09-15 | 1976-11-16 | Diamond Shamrock Corporation | Electrolysis cathodes having a melt-sprayed cobalt/zirconium dioxide coating |
| US4263353A (en) * | 1978-06-15 | 1981-04-21 | Eutectic Corporation | Flame spray powder mix |
| US4248679A (en) * | 1979-01-24 | 1981-02-03 | Ppg Industries, Inc. | Electrolysis of alkali metal chloride in a cell having a nickel-molybdenum cathode |
| US4230748A (en) * | 1979-08-15 | 1980-10-28 | Eutectic Corporation | Flame spray powder mix |
-
1981
- 1981-02-21 DE DE19813106587 patent/DE3106587A1/en active Granted
-
1982
- 1982-01-27 DE DE8282100543T patent/DE3270538D1/en not_active Expired
- 1982-01-27 EP EP82100543A patent/EP0058832B1/en not_active Expired
- 1982-01-27 AT AT82100543T patent/ATE19268T1/en not_active IP Right Cessation
- 1982-02-18 US US06/349,839 patent/US4392927A/en not_active Expired - Lifetime
- 1982-02-19 NO NO820534A patent/NO158548C/en unknown
- 1982-02-19 CA CA000396683A patent/CA1207706A/en not_active Expired
- 1982-02-19 JP JP57025856A patent/JPS57177983A/en active Granted
- 1982-02-19 BR BR8200929A patent/BR8200929A/en unknown
- 1982-02-20 KR KR8200746A patent/KR890001217B1/en active
Also Published As
| Publication number | Publication date |
|---|---|
| DE3270538D1 (en) | 1986-05-22 |
| KR890001217B1 (en) | 1989-04-27 |
| EP0058832B1 (en) | 1986-04-16 |
| BR8200929A (en) | 1982-12-28 |
| NO820534L (en) | 1982-08-23 |
| NO158548C (en) | 1988-09-28 |
| US4392927A (en) | 1983-07-12 |
| NO158548B (en) | 1988-06-20 |
| EP0058832A3 (en) | 1982-09-29 |
| JPH0128115B2 (en) | 1989-06-01 |
| EP0058832A2 (en) | 1982-09-01 |
| KR830009267A (en) | 1983-12-19 |
| ATE19268T1 (en) | 1986-05-15 |
| DE3106587C2 (en) | 1987-01-02 |
| DE3106587A1 (en) | 1982-09-02 |
| JPS57177983A (en) | 1982-11-01 |
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